Waterproof watch case

ABSTRACT

Deterioration of the performance of a watch as the result of fine shavings produced in the assembly of a threaded case-body and a threaded case-back is avoided by interposing an annular ring of a metal of the same hardness as the case-back. Watertightness of the watch is achieved by seating both the case cover and case-back on a gasket.

United States Patent Fujimori [54] WATERPROOF WATCH CASE [72] Inventor: Yoshhld Flflimorl, Suwa, Japan [73] Assignee: Klbuslliki Knish: Suwa Seflrmha, Tokyo,

I Japan 22 Filed: Much 12,1970

[2 1] Appl. No.: 18,991

[30] v Foreign Application Priority Data March 28,1969 Japan ..44/27o92 s21 u.s.'ci. ..58190R 51 1m. 01. ..G04b 37/08 [58] muse-n11..." ...58/88 R,88 G, 88 W; 90R

[56] Rm cm uum-zo STATES PATENTS 3,006,139 10/1961 Hug et al ..58/90 R 1451 July 18, 1972 2,553,012 5/1951 Schwaibold ..58/88W FOREIGN PATENTS OR APPLICATIONS 387,549 5/1965 Switzerland -.58/90 R Primary Eraminer-Richard B. Wilkinson Assistant Examiner-George H. Miller, Jr. ArtorneyBlum, Moscovitz, Friedman & Kaplan 57 ABSTRACT Deterioration of the performance of a watch as the result of fine shavings produced in the assembly of a threaded casebody and a threaded case-back is avoided by interposing an annular ring of a metal of the same hardness as the case-back. Water-tightness of the watch is achieved by seating both the case cover and case-back on a gasket.

3 Claims, 2 Drawing figures PATENTED JUL 1 8 1912 6 3.6763996 FlG./

PRIOR ART WATERPROOF WATCH CASE BACKGROUND OF THE INVENTION In the construction of a conventional waterproof watch, the metals of which the case-body and case-back are made may differ in hardness. Where these components are joined by mating screw-threads, and where the metals are of different hardnesses, then burrs or shavings may be produced during the assembly of these components. Such burrs or shavings may enter the watch movement, and degrade the performance of the watch.

SUMMARY OF THE INVENTION V The production of burrs during the assembly of a case-body and a case-back is avoided by providing a threaded annular ring fixed to the case-body by adhesive or welding where the ring and the case-back are of metals of equal hardness and the thread on the ring mates with the thread on the case-back. A water-tight seal is provided by means of a gasket on which both the case-body and the case-back are seated.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross sectional view showing a conventional waterproof watch case;

FIG. 2 is a cross sectional view showing a waterproof watch case according to the invention.

. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved waterproof watch case wherein case body and case back are engaged by means of threads.

FIG. 1 shows a construction of a conventional waterproof watch case. 1 is a case body of a waterproof watch case; threads 2 provided directly on the inner surface of said case body I; 3 a case back. Threads 4 provided on the outer surface of the case back 3 engages the threads 2 on the case body 1. 5 is a gasket. Waterproofing is maintained in such a manner that gasket 5 is pressed by engaging the threads 2 on the case body 1 with the threads 4 on the case back 3 and tightening the case back 3. Since the threads 2 is provided directly on the case body I, the threads and the case body 1 are made of the same material. If the hardness of the material of the case body 1 differs from that of the case back 3, for example, the case body is made of softer material than that of the case back or the case body is harder than the case back, the softer material is scraped off when tightening the threads 2 on the case body 1 with the threads 4 on the case back. The burr drops inside the case and causes the watch to stop or deteriorates the quality of the watch.

In case the case body is made of hard material, it is impossible to cut the threads 2 on the case body 1. In order to avoid the threads structure, a complicated structure without threads is devised or a one-piece case in which case back 3 and casebody I in one body is employed, which results in low productivity and high cost. The present invention seeks to eliminate such defect.

Referring now to the drawing, which describes one embodiment according to the invention:

In FIG. 2, 6 is a case body of waterproof watch case, 7 a circular ring provided with threads 8, 9 a case back, threads 10 provided on the outer surface of the case back so as to engage with the threads 8 of the ring. 11 is a gasket. Ring 7 is fixed to the inner surface of the case body 6 by means of welding or adhesives, etc. The ring is made of the material having the same hardness as the threads 10 of the case back regardless of the material of the case body 6. Waterproofing is maintained in such a manner that the threads 10 on the case back 9 engage the threads 8 on the ring 7 fixed to the case body 6 and the gasket 1 l is pressed by closing the case back 9.

As can be seen from the above description, in the present invention, on the inner surface of the case body 6, there is fixed the annular ring rovided with the threads 8 which engage the threads 10 o the case back 9 and having the same hardness as the threads 10 of the case back.

Being so constructed, regardless of the fact whether the material of the case body 6 is softer or harder than that of the case back 9, no burr will be produced on the threads portion when tightening the case back 9. As a result, trouble due to the burr is eliminated and the quality of the watch is greatly increased.

In order to make a case body 6 from hard material to produce a scratchproof watch, the conventional case back 9 can be used and it is sufficient to fix the ring 7 to the inner surface of the case body 6 without requiring a complicated structure. As a result, productivity is greatly increased and the cost is reduced.

What is claimed is:

l. A water-proof watch case comprising a case-body having rearwardly facing spaced-apart first and second internal shoulders therein, an internally threaded ring affixed internally to said case-body in the space between said first and second shoulders, a case-back externally-threaded to mate with the threads of said ring, an external flange on said case-back rearward of the threads of said case-back, and a gasket of size and shape to engage said flange and said second shoulder thereby providing a watevtight seal between said case-body and said case-back, said case-back and said ring being of essentially equal hardness and differing in hardness from the hardness of said case-body.

2. A water-proof watch case as defined in claim 1, wherein said ring abuts said first shoulder.

3. A water-proof watch case as defined in claim 2, wherein the axial length of said ring is essentially equal to the distance between said shoulders, whereby said ring bears on said gasket when said case-body and said case-back are threadedly joined. 

1. A water-proof watch case comprising a case-body having rearwardly facing spaced-apart first and second internal shoulders therein, an internally threaded ring affixed internally to said case-body in the space between said first and second shoulders, a case-back externally-threaded to mate with the threads of said ring, an external flange on said case-back rearward of the threads of said case-back, and a gasket of size and shape to engage said flange and said second shoulder thereby providing a water-tight seal between said case-body and said case-back, said case-back and said ring being of essentially equal hardness and differing in hardness from the hardness of said case-body.
 2. A water-proof watch case as defined in claim 1, wherein said ring abuts said first shoulder.
 3. A water-proof watch case as defined in claim 2, wherein the axial length of said ring is essentially equal to the distance between said shoulders, whereby said ring bears on said gasket when said case-body and said case-back are threadedly joined. 